In a common cycloid pinwheel reducer, an input shaft is mounted in a support with bearings, an eccentric shaft is positioned on the input shaft and assembled with two cycloid pinwheels, and the two cycloid pinwheels are connected to an output shaft. In use, the input shaft rotates the cycloid pinwheels via the eccentric shaft, and the output shaft rotates together with the eccentric shaft. However, the cycloid pinwheel reducer is difficult to engage with other transmission structures to reduce speed in a multiple speed reducing process. In addition, a structure engagement of the transmission structures and the input shaft is not compact enough, thus causing the cycloid pinwheel reducer to require to occupy larger amount of space.
Therefore, there is room for improvement within the art.